This section provides background information to facilitate a better understanding of the various aspects of the disclosure. It should be understood that the statements in this section of this document are to be read in this light, and not as admissions of prior art.
Hydraulic fracturing is a process of pumping liquids down a well and into a subterranean formation at high rate and pressure, such that a fracture is formed in the rock around the well. After pumping a liquid volume sufficient to widen the fracture adequately, solid particles, called “proppant,” are added to the liquid and placed in the fracture to prevent the rock fractures from closing and allowing the oil and/or gas flowing through the fractures into a wellbore for production of the hydrocarbons. The production rate and production service of fluid from the well is usually significantly increased after the fracturing treatment. Vast improvements in the hydraulic fracturing process have been developed since the process was originally patented in 1949.
The material first used for proppant in hydraulic fracturing of wells was silica sand. As wells became deeper, sand was sometimes found to have inadequate strength or other properties. For example, in deep wells, stress of the earth would cause the sand to crush and become much less effective in increasing the production rate of a well. In turn, synthetic proppant materials were developed to provide higher strength proppants. One type of synthetic proppant was sintered bauxite. In later years, a variety of ceramic raw materials have been used to make sintered ceramic proppants, including bauxite containing alumina and clay minerals, such as kaolin.
Ceramic proppant is produced by a variety of techniques, one of them being extrusion. Due to the use of various minerals, the rheology of the ceramic slurry, which passes through the extruder, may create, and require, very high pressure. Such high pressure increases the potential for equipment abrasion, reduces potential extrusion process output, and may lead to increased power consumption, as well as the requirement for heavy and expensive mechanical construction of all parts of the extruder.
Thus, there remains a continuing need to develop compositions and techniques used in the preparation of synthetic proppants in order to reduce high-pressure requirements during the extrusion process, such need met at least in part by the following disclosure.